Magnetically actuated devices may be designed for a variety of purposes such as, e.g., electrical switching, position sensing, snychronization, flow measurement, and stirring. Particularly important among such devices are so-called reed switches as described, e.g., in the book by L. R. Moskowitz, Permanent Magnet Design and Application Handbook, Cahners Books, 1976, pp. 211-220; in U.S. Pat. No. 3,624,568, issued Nov. 30, 1971 to K. M. Olsen et al., in U.S. Pat. No. 3,805,378, issued Apr. 23, 1974 to W. E. Archer et al.; and in the paper by M. R. Pinnel, "Magnetic Materials for Dry Reed Contacts", IEEE Transactions on Magnetics, Vol. MAG-12, No. 6, Nov. 1976, pp. 789-794. Reed switches comprise flexible metallic reeds which are made of a material having semihard magnetic properties as characterized by an essentially square B-H hysteresis loop and high remanent induction B.sub.r ; during operation reeds bend elastically so as to make or break electrical contact in response to changes in a magnetic field.
Among established alloys having semihard magnetic properties are Co-Fe-V alloys known as Vicalloy and Remendur, Co-Fe-Nb alloys known as Nibcolloy, and Co-Fe-Ni-Al-Ti alloys known as Vacozet. These alloys possess adequate magnetic properties; however, they contain substantial amounts of cobalt whose rising cost in world markets causes concern. Moreover, high cobalt alloys tend to be brittle, i.e., to lack sufficient cold formability for shaping, e.g., by cold drawing, rolling, bending, or flattening.
Relevant with respect to Fe-Cr-Mo alloys are the book by R. M. Bozorth, Ferromagnetism, Van Nostrand, 1959, p. 418 and the paper by E. Scheil et al., "Ausscheidungshartung bei Eisen-Chrom-Molybdan-und Eisen-Chrom-Wolfram-Legierungen", Archiv fur das Eisenhuttenwesen, Vol. 7, No. 11, May 1934, pp. 637-640. Phase diagrams of Fe-Cr-Mo alloys appear in Metals Handbook, American Society for Metals, Vol. 8, 1973, pp. 421-422.